Conventional toothbrushes comprise uniform tufts of bristles each having a first end which is held captive in and fixed to a brush head, and a second end which is free and which is used for brushing. The free ends of the various tufts present a surface envelope which is capable of slight deformation by the bristles bending when they come in contact with a surface to be brushed, but which is incapable of adequately matching a surface having a complex shape with varying levels. Such a complex surface is present in the mouth, wherein the teeth generally lie in a "C" shaped curve within the upper and lower jaw, each row of teeth consequently having a convex outer curve and a concave inner curve. Further, the teeth themselves are contoured in an arcuate shape having significantly varying levels, including a deep "V" shaped interproximal area between one tooth and the next.
The desire of users to cause the bristles to conform to the teeth and to penetrate the interproximal spaces between the teeth is expressed by the forceful application of the brush to adequately deform the bristles to the arcuate contours of the dentiture. Such forceful application of the brush against the teeth merely leads to excessive wear of the tooth surfaces and gums, without adequate conformation of the brush about and between the teeth to provide the desired cleaning.
Toothbrushes such as those disclosed in PCT WO 98/35584, having bristle tufts capable of a toggling movement partially address the above problem. PCT WO 98/35584 discloses bristle tufts mounted in a resilient material held within an array of rigid receptacles or wells whose connection to the overall frame or skeleton of the brush has been broken. As the tufts are solely connected to the brush by the resilient material they will independently toggle or move in all planes (upwards/downwards/sideways). However, such independent motion of the bristles will not cause them to conform to the configuration of the teeth.
U.S. Pat. No. 4,633,542 discloses a toothbrush in which the bristles are slidably mounted within a rigid head, resting upon a resiliently deformable membrane. There is a cavity within the head of the toothbrush below the membrane, such that the bristles are resiliently forced into the head as the bristles are applied to the teeth. This independent motion of the bristles, in one plane, will not cause them to conform to the sloping, arcuate, surfaces of the teeth.
U.S. Pat. Nos. 5,355,546, 5,483,722 and 5,839,149 disclose toothbrushes whose head is formed of a rigid frame supporting a flexible resilient member which has a series of linearly parallel lines or arrays of bristle tufts, which lines of bristle tufts are oriented along the longitudinal axis of the toothbrush. In each of the these patents the parallel lines of bristles are flexibly mounted, such that in brushing when a tooth is forced against the center line of tufts, that line of tufts will yield away from the tooth, causing the adjacent lines of bristle tufts to orient themselves about the sides of the tooth. As this contouring about the tooth is in two dimensions, these patents fail to address the overall three dimensional curvature of the teeth, especially the deep "v" shaped interproximal area between one tooth and the next.
U.S. Pat. No. 5,651,158 discloses a flexible head toothbrush having many embodiments, including a first embodiment in which the bristles may be mounted on head segments linked by grooves or thinned, i.e. flexible, connections which may be filled with a resilient elastomer. A second embodiment comprises a toothbrush head having bristle mounting segments within a hard peripheral frame, the segments being linked at planar points located 90.degree. to the longitudinal axis of the handle, the linkage being of thinned sections such that the segments may be made to rock about these links, in addition to flexing. A third embodiment includes a hard peripheral frame containing a toothbrush head formed of one or more chains of bristle carriers, flexibly and resiliently linked to each other and linked to at least one end of the frame. A fourth embodiment is formed of segments which are not joined to each other, but are flexibly and resiliently linked to the handle or to the frame, wherein the linkage to the frame may be by thinned sections or spines. In each embodiment the various segments or bristle carriers will flex independently or at most in coordination with the adjacent segments or bristle carriers within the chain of bristle carriers; such limited coordination of the orientation of the bristle tufts about the tooth will not provide the conformation to the various arcuate surfaces of the tooth surfaces necessary for effective cleaning.
There is a need for a toothbrush, wherein the bristles coordinate their orientation to conform to the three dimensional arcuate tooth surfaces and the deep "v" shaped interproximal area between one tooth and the next, such as to provide effective overall cleaning.